1. Field of the Invention
The present invention relates to a drum type washing machine, more particularly, to a drum type washing machine having an improved structure of a driving part.
2. Discussion of the Related Art
In general, a drum type washing machine is classified into an indirect drive motor drum type washing machine and a direct drive motor drum type washing machine. In the indirect drive motor drum type washing machine, driving power of a motor is indirectly transmitted to a drum via a motor pulley and a belt wound around a drum pulley. Whereas, in the direct drive motor drum type washing machine, a rotor of a BLDC motor (Brushless DC motor) is directly connected to a drum to transmit driving power of a motor to a drum.
The indirect drive motor drum type washing machine may cause energy loss or severe noise in the process of transmitting the driving power, because the driving power is not directly transmitted to the drum, but indirectly transmitted to the drum via the motor pulley and the belt.
Thus, to solve the above problem, demands for a direct drive motor drum type washing machine (hereinafter, a DDM drum type washing machine) have been accordingly increasing, which adapts a BLDC motor.
Referring to FIG. 1, a structure of a conventional DDM drum washing machine will be described briefly.
FIG. 1 is longitudinally sectional view of a conventional drum type washing machine. The conventional drum type washing machine includes a cabinet 1, a tub 2 mounted within the cabinet 1 and a drum rotatably mounted within a center of the tub 2.
A motor having a stator 6 and a rotor 5 is mounted in a rear of the tub 2. The stator 6 is fixed to a rear wall of the tub 2 and the rotor 5 is fastened to the drum 3 by a shaft 4, passing through the stator.
FIG. 2 is a cut-away perspective view illustrating some portion of a rear wall of the tub.
Here, a bearing housing 7 is provided in the rear wall center of the tub 2 to support a bearing as well as to fasten the stator 6 to the tub 2. The bearing is installed on each outer circumferential surface of both terminal ends of a shaft 4.
The rear wall of the tub 2 includes a step part 21 and a non-step part 22. A fastening part 23, which will be described later, is stepped on a center portion of the step part 21, where the bearing housing 7 is provided, to be fastened to the stator 6. A plurality of reinforcement ribs 22a are formed on the non-step part 22.
FIG. 3 is a perspective view illustrating an exterior of the stator 6. The conventional stator 6 includes a core part 61 having a ring shape for winding a coil 66 thereto, an insulator 62 and 63, a hall sensor assembly 64 and a tap housing assembly 65 for power connection.
The insulator 62 and 63 includes a first insulator 62 and a second insulator 63 for covering an upper and lower surface of the core part 6. A plurality of projection parts 62a and 63a are projected toward a center of the first and second insulator 62 and 63 to form a fastening hole 62b and 63b therein. The projection part 62a and 63a may be formed as one body with the first and second insulator 62 and 63, or alternatively some portion of the core part 61 may projected to form the projection part 62a and 63a. 
Each fastening hole 62b and 63b is fastened to the fastening part 22 of the tub rear wall by a bolt.
At that time, a plurality of position determination protrusions 62c are formed on the projection part 62a of the first insulator 62 to determine the position where the stator 6 is fastened to the tub 2. A plurality of position determination holes 23a are formed on the fastening part 23 of the tub rear wall to insert the position determination protrusions 62c therein.
Thus, after the position of the stator 6 is determined by the position determination protrusions 62c and holes 23a, the stator 6 and the tub 2 are fastened each other through the fastening holes 62b and 63b. 
However, since in the fastening structure between the stator 6 and the tub 2 each position determination protrusion 62c is formed in a pin shape having a narrow diameter, there is a problem that the position determination protrusion 62c may be easily damaged during the assembly or the transportation thereof.
Due to the damage of the position determination protrusion 62c, the process of fastening the stator 6 to the tub 2 may not be performed smoothly.
Specifically, in a drum type washing machine which directly rotates a drum 3 by using a BLDC motor as shown in FIG. 4, the stator 6 is directly fastened to a fixed portion of the tub rear wall. But, since the weight of only the stator is 1.5 kg and the spinning rotation speed of a motor for a drum type washing machine having a large capacity is 600˜2,000 RPM. Thus, the fastening portion between the stator 6 and the tub 2 is easily damaged due to the weight of the stator 6, vibration in high speed rotation, and shake/deformity of the rotor 5.
Still more, since in a drum type washing machine which uses a BLDC motor and fastens the stator 6 to the tub 2, the radius direction of the stator 6 is perpendicular to the floor, the damage of the fastening portion between the stator 6 and the tub 2 may getting severed.
Accordingly, a tub supporter (not shown) made of metal for covering most of the tub rear wall should be arranged between the tub 2 and the stator 6 to prevent the damage. However, in that case, an additional assembly work for fastening the tub supporter to the tub rear wall should be added, such that a disadvantage of low productivity may be caused thereby.